1. Field of the Invention
The present invention relates to a dynamoelectric rotor that is mounted to a vehicle such as a passenger car, or a truck, etc., for example.
2. Description of the Related Art
In conventional automotive alternator rotors, a field coil is wound onto a cylindrical boss portion. Thus, if the rotational acceleration changes greatly, a force acts that rotates the field coil relative to the boss portion due to inertia of the field coil. If this force is great, the field coil may rotate relative to the boss portion, giving rise to misalignments. When misalignments of this kind occur, there is a risk that conducting wires that connect the field coil and slip rings that rotate together with the boss portion may break. When these conducting wires break, changes in magnetic flux no longer occur in the armature, and function as an alternator can no longer be achieved.
In view of these conditions, various rotors have been proposed to prevent rotation of the field coil relative to the boss portion.
In a first conventional rotor, a rotor core is configured so as to be divided into three parts that include: a boss portion onto which a field coil is wound; and a pair of pole cores that are disposed on two sides of the boss portion, and the boss portion is formed so as to have a polygonal prism shape. The field coil is wound onto the boss portion with an insulating material interposed (see Patent Literature 1, for example).
In a second conventional rotor, a rotor core is also configured so as to be divided into three parts that include: a boss portion on which a field coil is wound; and a pair of pole cores that are disposed on two sides of the boss portion. The boss portion is formed so as to have a polyhedral shape that have a plurality of inclined surfaces as side surfaces in which first and second congruent polygonal end surfaces that have rotational symmetry that is centered around a rotating shaft are disposed so as to be rotated around the rotating shaft such that corner portions of the first end surface are positioned centrally on edge portions of the second end surface and the corner portions of the polygons of the first and second end surfaces are formed so as to be joined in a zigzag, and the field coil is wound on the boss portion with an insulating material interposed (see Patent Literature 2, for example).
Patent Literature 1: Japanese Utility Model Publication No. SHO 42-2570 (Gazette)
Patent Literature 2: Japanese Patent No. 3041881 (Gazette)
In both of these conventional rotors, because the rotor cores are configured so as to be divided into three parts that include a boss portion and first and second pole cores that are disposed on two sides of the boss portion, one problem has been that assembly deteriorates as the number of parts is increased.